Waveguides convey electromagnetic transmission between locations. Waveguides can rely on total internal reflection to provide high transmission characteristics. Reducing impurities in the waveguide transmission material can increase the transmission percentage. Maintaining the cross-sectional configuration of the waveguide is critical to limit transmission losses, so discontinuities in peripheral walls of waveguides are limited.
Transitioning between waveguides with different configurations and/or materials provides a potential source for energy loss and signal degradation. A variety of waveguide couplers limit losses of the energy of the waves traversing between waveguides.